1. Field of the Invention
The present invention relates to a graphene pattern and a process of preparing the same, and more particularly, to a graphene pattern formed in a predetermined shape on a substrate and a process of easily preparing the graphene pattern.
2. Description of the Related Art
Generally, graphite is a stack of two-dimensional graphene sheets formed from a planar array of carbon atoms bonded into hexagonal structures. Recently, as a result of testing properties of single-layered or several-layered graphene sheets, their beneficial properties have been revealed.
The most noticeable beneficial property is that electrons flow in a graphene sheet as if they are weightless, which means that electrons flow at the velocity of light in a vacuum. In addition, an unusual half-integer quantum hall effect for both electrons and holes is observed in the graphene sheet.
An electron mobility of known graphene sheets is about from 20,000 to 50,000 cm2/Vs. Also, it is advantageous to use graphene sheets since products made from graphite are inexpensive while products made from carbon nanotubes which are similar to graphene sheets are expensive due to low yields obtained during synthesis and purification processes even though the carbon nanotubes are inexpensive themselves. Single wall carbon nanotubes exhibit different metallic and semiconducting characteristics according to their chirality and diameter. Furthermore, single wall carbon nanotubes having identical semiconducting characteristics have different energy band gaps depending on their chirality and diameter. Thus, single wall carbon nanotubes are required to be separated from each other in order to obtain desired semiconducting or metallic characteristics. However, separating single wall carbon nanotubes is not a simple process.
On the other hand, it is advantageous to use graphene sheets since a device can be easily designed to exhibit desired electrical characteristics by arranging the crystalline orientation in a desired direction since electrical characteristics of a graphene sheet are changed according to the crystalline orientation. The characteristics of the graphene sheet can be efficiently applied to carbonaceous electrical devices or carbonaceous electromagnetic devices in the future.
However, although the graphene sheet has these advantageous characteristics, a method of economically and reproducibly preparing a large-area graphene sheet has not been developed yet. The methods of preparing a graphene sheet are classified into a micromechanical method and a SiC thermal decomposition. According to the micromechanical method, a graphene sheet separated from graphite can be prepared on the surface of a Scotch™ tape by attaching the tape to a graphite sample and detaching the tape. In this case, the separated graphene sheet does not include a uniform number of layers, and does not have a uniform shape of tipped portions. Furthermore, a large-area graphene sheet cannot be prepared. Also, according to the SiC thermal decomposition, a SiC single crystal is heated to remove Si by decomposition of the SiC on the surface thereof, and then residual carbon C forms a graphene sheet. However, the SiC single crystal which is used as a starting material used in the SiC thermal decomposition is very expensive, and a large-area graphene sheet cannot be easily prepared.
Therefore, it is not easy to prepare a graphene sheet, and the graphene sheet cannot be easily patterned on a substrate.